Arrays of biopolymeric binding agents, such as oligonucleotides and peptides, have become an increasingly important tool in the biotechnology industry and related fields. These binding agent arrays, in which a plurality of binding agents are present on a solid support surface in the form of an array or pattern, find use in a variety of applications, including genomomics and proteomics applications, e.g., gene expression analysis, drug screening, nucleic acid sequencing, mutation analysis, proteome analysis, and the like.
Such arrays may be prepared in a number of different ways. For example, DNA arrays may be prepared manually by spotting DNA onto the surface of a substrate with a micro pipette. See Khrapko et al., DNA Sequence (1991) 1:375-388. Alternatively, the dot-blot approach, as well as the derivative slot-blot approach, may be employed in which a vacuum manifold transfers aqueous DNA samples from a plurality of wells to a substrate surface. In yet another method of producing arrays of biopolymeric molecules, a pin is dipped into a fluid sample of the biopolymeric compound and then contacted with the substrate surface. By using a plurality or array of pins, one can transfer a plurality of samples to the substrate surface at the same time. Alternatively, an array of capillaries can be used to produce biopolymeric arrays. See WO 95/35505. In another method of producing biopolymeric arrays, arrays of biopolymeric agents are “grown” on the surface of a substrate in discreet regions. See e.g. U.S. Pat. No. 5,143,854 and Fodor et al., Science (1991) 251:767-773.
One type of biopolymeric array fabrication process of particular interest is the jet printing fabrication protocol, in which thermal or piezo pulse jet devices analogous to inkjet printing devices are employed to deposit fluids of biopolymers or precursors therefore onto a substrate surface. For example, Roda et al., Biotechniques (2000) 28:492-496, describe a method in which a conventional inkjet printer is used for the microdeposition of proteins. In this report, the black ink was removed from a Hewlett Packard ink cartridge and the cartridge was extensively washed with water. The cartridge was filled with the protein deposition solution using a microsyringe and sealed. Similarly, Deeg et al. in U.S. Pat. No. 5,338,688, describe a method of using bubble-jet technology for the metered application of an analytical liquid to a target. This disclosed method is based on the manufacture of disposable jet units containing the analytical liquid in prepacked form. Additional U.S. Patents disclosing thermal and/or piezo pulse jet deposition of biopolymer containing fluids onto a substrate include: U.S. Pat. Nos. 4,877,745; 5,449,754; 5,474,796; 5,658,802; 5,700,637; and 5,958,342.
Despite the advances made to date in the arena of pulse jet printing of biopolymeric arrays, there is a continued need for improvement in this field. Of particular interest would be the development of highly accurate pulse jet printing devices that are able to print a multitude of different fluids at the same time, where the devices require little maintenance and yet produce high quality, dense arrays.
Relevant Literature
U.S. Pat. Nos. 4,877,745; 5,449,754; 5,474,796; 5,658,802; 5,700,637; and 5,958,342; 6,221,653; and 6,242,266. Additional U.S. Patents of interest that describe traditional thermal inkjet devices and methods for their use in ink deposition include: U.S. Pat. Nos. 4,500,895; 4,771,295; 5,278,584; 5,305,015; 6,155,675; 6,155,676; 6,183,067; 6,290,331; See also: The Hewlett-Packard Journal, Vol. 39, No. 4 (August 1988).